In the world of sci-fi movie geekdom, August 29, 1997, was a turning point for humanity: On that day, according to the Terminator films, the network of US defence computers known as Skynet became self-aware - and soon launched an all-out genocidal war against Homo sapiens.

Fortunately, that date came and went with no such robo-apocalypse. But the 1990s did bring us the World Wide Web, which is now far larger and more "connected" than any nation's defence network. Could the internet "wake up"? And if so, what sorts of thoughts would it have? And would it be friend or foe?

Neuroscientist Christof Koch believes we may soon find out - indeed, the complexity of the web may have already surpassed that of the human brain. In his book Consciousness: Confessions of a Romantic Reductionist, published earlier this year, he makes a rough calculation: Take the number of computers on the planet - several billion - and multiply by the number of transistors in each machine - hundreds of millions - and you get about a billion billion, written more elegantly as 10 to the 18th. That's a thousand times larger than the number of synapses in the human brain (about 10 to the 15th).

Koch, who taught for more than 25 years at the California Institute of Technology and is now chief scientific officer at Seattle's Allen Institute for Brain Science, is known for his work on the "neural correlates" of consciousness - studying the brain to see what's going on when we have specific conscious experiences. Of course, our brains happen to be soft, wet and made of living tissue, while the internet is made up of metal chips and wires - but that's no obstacle to consciousness, he says, so long as the level of complexity is great enough. (Most researchers working on artificial intelligence would agree that the "substrate" doesn't matter. That is, it makes no difference what the system is made of. Most philosophers, though not all, would agree.)

In a phone interview, Koch noted that the kinds of connections that wire together the internet - its "architecture" - are very different from the synaptic connections in our brains, "but certainly by any measure it's a very, very complex system. Could it be conscious? In principle, yes it can."

Of course, there's the tricky question of defining consciousness, but for our purposes it is enough to say that if an entity is conscious, then it "feels like" something to be that entity. Humans are conscious, at least while we're awake. Apes and monkeys, perhaps most animals, likely have some degree of consciousness. (Koch, a dog lover, does not hesitate to include our canine companions.) How consciousness actually works is far less clear, but Koch - going somewhat out on a limb - declares it to be a fundamental property of the universe, akin to energy, mass and space.

That doesn't mean that any physical system is automatically conscious - only that it has the potential to be conscious. It has to have sufficient complexity, and it has to be connected in just the right way. Does the internet meet those criteria?

"Even today it might 'feel like something' to be the internet," Koch says. Each computer feels nothing, of course, but the totality of the internet may be more than the sum of its parts. "That's true for my brain, too. One of my nerve cells feels nothing - but put it together with 100 billion other nerve cells, and suddenly it can feel pain and pleasure and experience the colour blue."

Would its first instinct be to kill off those pesky humans, as Skynet was so quick to do? Not necessarily. Our own evolution is an ongoing struggle that began some 2 billion years ago (if you start the clock when we were blue and green algae). By comparison, the internet of today is more like a newborn baby.

"It may not have any of the survival instincts that we have," Koch says. "It did not evolve in a world 'red in tooth and claw', to use Tennyson's famous expression." Should the internet achieve consciousness, it will - at least at first - be "utterly naive to the world". On the other hand, the internet has only existed for a couple of decades. "So who knows where it will be 20 years from now."

The science fiction writers have already explored this territory - not just in shoot-'em-ups like the Terminator films, but in more cerebral works like Robert J. Sawyer's WWW trilogy (the novels are titled Wake, Watch and Wonder). In Wake, the World Wide Web wakes up - and, after a bit of a learning curve, becomes the smartest entity on the planet.

Eerily, as Koch speculated on what the internet might "feel", he described a scenario straight out of Sawyer's trilogy (which he had not heard of until I mentioned it). Should there be a large power failure somewhere in the world, Koch said, a conscious internet could experience the equivalent of "pain". In Wake (published in 2009), the Chinese government shuts down an enormous swath of the internet to cover up a particularly nasty incident that it desperately wants to hide from the rest of the world. The still-nascent Webmind "feels" all that cutting and severing - and doesn't like it:

No!

Not just small changes.

Not just flickerings.

Upheaval. A massive disturbance.

New sensations: Shock. Astonishment. Disorientation. And -

Fear.

The WWW trilogy is a work of fiction, but for Sawyer, it's a plausible picture of what lies ahead in our increasingly wired world. We can't pin down the date when the internet surpasses our brains in complexity, he says, "but clearly it is going to happen at some point".

Even Koch admits that he doesn't lose any sleep over the possibility of the internet waking up. Sawyer, however, sees the web's continued growth as a very real potential threat. As the web grows more complex, at an accelerating pace, there is inevitably a "tipping point", he says. "There is a point after which you can't do anything about it. Should we be afraid of it? Absolutely."

Even if those fears prove to be unfounded, such questions are still worth pondering. If the internet doesn't have what it takes to become conscious, it would be useful to understand why it fails. Perhaps we can even come a little closer to learning how our brains manage to pull it off.